Optical and Electrical Characterization of ZnO:Ga₂O₃ Thin Films Synthesized by MASP for Oxygen Gas Sensor Applications
DOI:
https://doi.org/10.26740/jpfa.v15n2.p69-79Keywords:
ZnO:Ga₂O₃, thin film, Microwave-Assisted Spray Pyrolysis, oxygen sensor, medical ventilatorAbstract
This study investigates the effect of oxygen (O₂) exposure on the optical and electrical properties of ZnO:Ga₂O₃ thin films synthesized by the Microwave-Assisted Spray Pyrolysis (MASP) method. A 3% Ga₂O₃ doping level was used as the optimal composition to enhance the film’s stability and conductivity. After deposition and annealing at 450 °C, the films were exposed to O₂ gas at pressures ranging from 0 to 400 mTorr to evaluate their oxygen detection capability. Optical properties were characterized using UV–Vis spectroscopy, while electrical measurements were performed with an IV-meter employing the two-point probe method. The results show that the optical band gap increased from 3.19 eV to 3.23 eV with rising O₂ pressure due to the Burstein–Moss effect, indicating a shift of the Fermi level and carrier concentration change upon oxygen adsorption. Simultaneously, the electrical resistance increased from 1.05 × 10⁷ Ω to 1.25 × 10⁷ Ω, attributed to the formation of a surface depletion layer that reduces the density of free carriers. In addition, the sensitivity increased from 1.90% at 100 mTorr to 19.05% at 400 mTorr, indicating an increasingly pronounced electrical response with increasing oxygen pressure. The positive correlation between band gap and resistance confirms that oxygen exposure directly affects the film’s optoelectronic behavior. With high transparency, structural stability, and linear response to oxygen, the ZnO:Ga₂O₃ thin film demonstrates strong potential for real-time oxygen sensing applications.
References
[1] Guo, Y.-M., Liu, Z., Liang, Y., Yin, X., & Ma, B. (2026). Ppm-level photoacoustic oxygen gas sensor with a 3W red diode laser. Optics Express, 34(5), 7895–7903.
[2] P. K. Panigrahi, B. Chandu, and N. Puvvada, "Recent Advances in Nanostructured Materials for Application as Gas Sensors," ACS Omega, vol. 9, no. 3, pp. 3092–3122, Jan. 2024, doi: https://doi.org/10.1021/acsomega.3c06533.
[3] Bannunah, A. M. (2023). Biomedical applications of zirconia-based nanomaterials: challenges and future perspectives. Molecules, 28(14), 5428.
[4] Nadargi, D. Y., Umar, A., Nadargi, J. D., Lokare, S. A., Akbar, S., Mulla, I. S., ... & Chaskar, M. G. (2023). Gas sensors and factors influencing sensing mechanism with a special focus on MOS sensors. Journal of Materials Science, 58(2), 559-582.
[5] Fischer, D., Zagorac, D., & Schön, J. C. (2023). Fundamental insight into the formation of the zinc oxide crystal structure. Thin Solid Films, 782, 140017.
[6] Raha, S., & Ahmaruzzaman, M. (2022). ZnO nanostructured materials and their potential applications: Progress, challenges and perspectives. Nanoscale Advances, 4(8), 1868–1925. https://doi.org/10.1039/D1NA00880C
[7] Chen, Z., Wang, J., Wu, H., Yang, J., Wang, Y., Zhang, J., ... & Tang, Z. (2022). A transparent electrode based on solution-processed ZnO for organic optoelectronic devices. Nature Communications, 13(1), 4387.
[8] Zhu, J., Xu, Z., Ha, S., Li, D., Zhang, K., Zhang, H., & Feng, J. (2022). Gallium oxide for gas sensor applications: A comprehensive review. Materials, 15(20), 7339.
[9] Arifin, N. M., Mhd Noor, E. E., Mohamad, F., & Mohamad, N. (2024). The impact of spinning speed on n-TiO2/ZnO bilayer thin film fabricated through sol–gel spin-coating method. Coatings, 14(1), 73.
[10] Zhang, C., Cao, J., Zhang, Y., Li, X., Guan, Y., Wang, Y., Liao, Y., Xie, Z., Zhang, Y., Li, S., Tang, W., Hu, G., & Tan, C. K. (2025). Strain relaxation in α-(AlₓGa₁₋ₓ)₂O₃ thin films grown on M-plane and R-plane sapphire via metalorganic chemical vapor deposition. Journal of Alloys and Compounds, 1039, 183079. https://doi.org/10.1016/j.jallcom.2025.183079
[11] Yu, J., Han, W., Suleiman, A. A., Han, S., Miao, N., & Ling, F. C.-C. (2024). Recent advances on pulsed laser deposition of large-scale thin films. Small Methods, 8(3), Article 2301282. https://doi.org/10.1002/smtd.202301282
[12] Huang, T., Mo, C., Cui, M., Li, M., Ji, P., Tan, H., Zhang, X., Zhuge, L., & Wu, X. (2024). Ion behavior impact on ITO thin film fabrication via DC magnetron sputtering with external anode. Vacuum, 221, Article 112848. https://doi.org/10.1016/j.vacuum.2023.112848
[13] Toma, F. T. Z., Rahman, M. S., & Maria, K. H. (2025). A review of recent advances in ZnO nanostructured thin films by various deposition techniques. Discover Materials, 5(1), 60. https://doi.org/10.1007/s43939-025-00201-1
[14] Gunawan, H. D., Sulhadi., Marwoto, P., & Rifita, F. (2025). Physical Properties Of Zno: Ga₂O₃ Thin Film Prepared By Microwave-Assisted Spray Pyrolysis: The Role Of Ga₂O₃. International Journal of Research and Innovation in Applied Science, 10(5), 781–789. https://doi.org/10.51584/ijrias.2025.100500071.
[15] Feng, Y., Zhang, L., Chen, H., Zhang, L., Guo, X., Liu, X., & Guo, S. (2026). Effects of Sn doping content on the structure, morphology, optical and electrical properties of ITO thin films prepared by microwave-assisted spray pyrolysis. RSC advances, 16(8), 7538-7548.
[16] Jubu, P. R., Obaseki, O. S., Nathan-Abutu, A., Yam, F. K., Yusof, Y., & Ochang, M. B. (2022). Dispensability of the conventional Tauc’s plot for accurate bandgap determination from UV–vis optical diffuse reflectance data. Results in Optics, 9, 100273. https://doi.org/10.1016/j.rio.2022.100273.
[17] Mohan, A. C., Athira, A., Nair, B. P., et al. (2024). Multifaceted properties of Ni and Zn codoped MgO nanoparticles. Scientific Reports, 14, Article 32067. https://doi.org/10.1038/s41598-024-83779-5
[18] Nafiusokhib, N., Marwoto, P., Sulhadi, S., Astuti, B., Sugianto, S., Darsono, T., & Septiano, A. F. (2024). The Effect Of Annealing Temperature On The Properties Of Thin Zno Films Deposited Using Microwave-Assisted Spray Pyrolysis System. Jurnal Pendidikan Fisika dan Keilmuan (JPFK), 10(1), 56-80.
[19] Özmenteş, R., & Hassanien, A. S. (2025). Characterizations and optical discussions of thermally evaporated titanium dioxide thin films. Journal of Optics, 54(3), 1322-1340. https://doi.org/10.3390/en16062653.
[20] S. Vimala Gayathri and D. Subbulekshmi, "Fabrication and Characterization of Physical Vapour Deposition Derived Amorphous Co₁₇Fe₅₄Ni₂₉ Thin Film for Magnetic Sensing Applications," in IEEE Access, vol. 13, pp. 142961-142979, 2025, doi: https://doi/org/10.1109/ACCESS.2025.3597353.
[21] Tripathy, S. R., & Baral, S. S. (2025). Defect Engineering in Semiconductor Photocatalysts: Enhancing Photocatalytic Activity for Green Energy Production. Advanced Energy and Sustainability Research, 2500110. https://doi.org/10.1002/aesr.202500110.
[22] Zhang, Y., Zhang, Q., He, Y., Liu, X., Wu, Y., & Wang, C. (2023). The impact of oxygen on Ga doped ZnO film. RSC Advances, 13(12), 8463–8471. https://doi.org/10.1039/D2RA08263B.
[23] Cadatal-Raduban, M., Kato, T., Horiuchi, Y., Olejníček, J., Kohout, M., Yamanoi, K., & Ono, S. (2022). Effect of Substrate and Thickness on the Photoconductivity of Nanoparticle Titanium Dioxide Thin Film Vacuum Ultraviolet Photoconductive Detector. Nanomaterials, 12(1), 10. https://doi.org/10.3390/nano12010010.
[24] Sharma, D. K., Shukla, S., Sharma, K. K., & Kumar, V. (2022). A review on ZnO: Fundamental properties and applications. Materials Today: Proceedings, 49(8), 3028–3035. https://doi.org/10.1016/j.matpr.2020.10.238
[25] Prasad, S., Bansal, S., Mansoori, A., Bala, M., & Sharma, P. (2023). Effect of Annealing Temperature on Excitonic Binding Energy and Other Optical Properties of Mn-Ni Co-Doped Transparent ZnO Thin Films. Transactions of the Indian Ceramic Society, 82(1), 31-39.
[26] Arifin, N. M., Mhd Noor, E. E., Mohamad, F., Mohamad, N., & Mohamed Muzni, N. H. (2024). Enhancing the properties of nanostructure TiO2 thin film via calcination temperature for solar cell application. Energies, 17(14), 3415.
[27] Marasini, S., Pandey, S., Ram Ghimire, R., & Subedi, P. (2025). Effect of aluminum doping on the optical, electrical, and gas sensing properties of ZnO thin films. Progress in Physics of Applied Materials, 5(1), 1-9.
[28] Li, M., Liu, M., Qi, F., Lin, F. R., & Jen, A. K. Y. (2024). Self-assembled monolayers for interfacial engineering in solution-processed thin-film electronic devices: design, fabrication, and applications. Chemical reviews, 124(5), 2138-2204.
[29] Choi, A. R., Lim, D. H., Shin, S. Y., Kang, H. J., Kim, D., Kim, J. Y., ... & Oh, I. K. (2024). Review of material properties of oxide semiconductor thin films grown by atomic layer deposition for next-generation 3D dynamic random-access memory devices. Chemistry of Materials, 36(5), 2194-2219.
[30] Zhu, J., Xu, Z., Ha, S., Li, D., Zhang, K., Zhang, H., & Feng, J. (2022). Gallium Oxide for Gas Sensor Applications: A Comprehensive Review. Materials, 15(20), 7339. https://doi.org/10.3390/ma15207339
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Jurnal Penelitian Fisika dan Aplikasinya (JPFA)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Author(s) who wish to publish with this journal should agree to the following terms:
-
- Copyright of articles published in Jurnal Penelitian Fisika dan Aplikasinya (JPFA) is held by Jurnal Penelitian Fisika dan Aplikasinya (JPFA).
- The author(s) grant JPFA the right to publish, reproduce, distribute, and make the article available in all forms and media.
- The published article is licensed under a Creative Commons Attribution-Non Commercial 4.0 License (CC BY-NC) that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal for noncommercial purposes.
- Author(s) are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
The publisher publishes and distributes the article with copyright notice to Jurnal Penelitian Fisika dan Aplikasinya (JPFA) under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Abstract views: 17
